OSHA Handrail (top rail) 200lb exac

[Cassidy G]

OSHA Handrail (top rail) 200lb exact location.

Hi! Good day Engineers.

I am design a OSHA stairs with handrail. I'm confused about 200lb concentrated live load, downward or outward direction.


For example top rail length is 25ft. I am planning to distribute the 200lb over the total length of top rail. And it becomes 8lb/ft acting in the top rail total length.

Can anyone give me advice.

Thank you.

 

[r13]

Cassidy G,

Yes, it sounds high, but that's the rule of the game. An OSHA Q&A is linked FYI, Link.

 

[Cassidy G]

r13

Yes, Engineer. I already read that. When the time I changed the live load for threads, some of structural members are failed (pipes)

I used Staad.Pro to design the whole stair system stringers, threads, railings and landings.

I already understand the live loads for railings but not for threads and landings.

For example, 1 staircase has 15 threads. Each thread has dimension of 0.850mx0.250m. I apply 500psf (23.94 kPa) to each thread. It's like 518.58kg x 15 threads.

I understand that not all of the threads should carry live load at the same time.

So, I check it one by one. 1st thread only has live load, pass. 2nd thread only, pass. And so on. It pass/safe if the live load is applied only in 1 thread.

But I'm thinking what if 2 or more threads has live load in actual. Let say 3rd and last thread has live load in acutal. Therefore, I apply the live load in all threads at the same time to check if it is ok. Now some of structural members are failed.

Any advice. Thank you and God bless, Sir.

 

[Cassidy G]

I used software because my boss told me.

 

[r13]

Cassidy G,

One of the article mentioned an OSHA response which may help:

“Each stair can support at least five times the normal anticipated live load, but never less than a concentrated load of 1,000 pounds (454 kg) applied at any point.”

The 1,000-pound point load is meant to account for a 300-pound person potentially running down the stairs. The impact of their footfall in that scenario will be higher than if they were simply standing on a tread. OSHA further clarifies the criterion by providing an interpretation for this loading with the following response:

“The design of fixed stairways and their components must be based on their ultimate strength [yield stress (FY) or ultimate stress (FU)] and not on the allowable stresses as given in the Allowable Stress Design method of the American Institute of Steel Construction, Ninth Edition.”

 

[jimstructures]

Cassidy G,

The plates one steps on are treads not threads. Just FYI.

Jim

 

[Cassidy G]

r13

Yes, Sir. I understand this “Each stair can support at least five times the normal anticipated live load, but never less than a concentrated load of 1,000 pounds (454 kg) applied at any point.”

I'm just thinking where I should apply the live load. Just like what I have said, I'm designing the whole staircase in software (Staad.Pro). I already check one by one. Live load placed at first tread (pass/safe). Live load placed at 2nd tread (pass/safe) and so on. The design of whole staircase is pass and safe if live load will apply one by one, like a person walking/running up and down the stairs.

But I'm thinking that not all the time one person will only use the stairs. What if 2 or more.

Let say the stairs has 15 treads. Person A used the stairs going up and when he/she stands exactly at 10th tread, person B used also the stairs. The treads can carry the 1000lbs but not the stringers. With person A and B, it's like stringers should resist 2*1000lbs.

I'm sorry, I'm not just asking for treads this time. I'm also asking for stringers since I already check the treads one by one.

Thank you, Sir.

 

[Cassidy G]

jimstructures

Yes, wrong spelling.

Thank you.

 

[r13]

I've came to a realization after the OSHA's response:

1. Design the individual tread for a concentrate load 300*5 = 1500# > 1000#. 300# concentrate load is typically required by the building code.
2. Apply 100*5 = 500# everywhere on the stair to design all other components.

I think you shall treat the above loads as factored )ultimate) loads (LF = 5), and use LRFD design method.